This invention relates generally to novel and improved brake equipment for rail vehicles and more particularly to independent brake control in computer controlled brake equipment located on the locomotive and arranged to control the application and release of the brakes of such locomotive, any trailing locomotive, and any cars coupled to either.
Prior art brake equipment for locomotives has typically been implemented with mechanical and pneumatic hardware, as, for example, the 26-L brake equipment of New York Air Brake Company of Watertown, N.Y. As illustrated in FIG. 1, this prior art brake equipment employs as major components a 26-C brake valve 30 including an independent brake valve SA-26, a 26-F control valve 33 and a J relay valve 37 interconnected with various pneumatic pipes represented by solid lines. The brake valve 30 responds to movement by the train operator of an automatic brake handle 31 to regulate pressure in a brake pipe 40 by means of an equalization reservoir 36 and a brake pipe relay in the brake valve 30 for application and release of brakes on the locomotive, the brakes of any trailing locomotive and the brakes of cars coupled to either.
The automatic brake handle has six positions as illustrated by the sector diagram in FIG. 2. The brake valve 30 also responds to movement of an independent brake handle 32 by the train operator to control the application and release of the locomotive brakes independently of the train brakes and for bailing-off or releasing an automatic brake application of the locomotive independently of the train brakes by way of the 26-F control valve 33 and the J relay 37.
The independent brake handle 32 has two extreme positions, Release and Full Application separated by an application zone as shown in FIG. 2. As the handle is moved from the Release position through the application zone toward the Full Application position will apply the locomotive brakes. The independent handle 32 can be depressed so as to cause a bailing-off or the release of any automatic brake application existing on the locomotive (due to operation of the automatic brake handle 31). This is effected via the 26-C brake valve 30 and the 26-F control valve 33. If the independent brake handle 32 is in an Application position, the locomotive brake will be applied according to the higher of independent or automatic brake.
The 26-F control valve 32 and auxiliary reservoir 36 respond to service and emergency rates of brake pipe pressure reduction (brake applications) to control the locomotive brake cylinder pressure via the J relay valve 37. The 26-F control valve 33 also responds to a brake release operation of the independent brake handle 32 to control locomotive brake cylinder pressure to release the locomotive brakes following an automatic brake operation at the service and emergency rate developed by operation of the automatic brake handle 31. A key element of the 26-F control valve 30 is a double check valve 34 which applies to the J relay valve 37 the higher of the pressures developed by the 26-F control valve 33 or by the independent application and release pipe 42.
The J relay valve 37 is a volume amplifier that operates to translate the pressure at a smaller volume input to a desired pressure at a larger volume output. As the desired output pressure can differ for different locomotive (different sized brake cylinders), it has been necessary to select a particular J relay valve for a particular locomotive specification.
The P2-A valve 35 is a brake application or penalty valve responsive to unsafe conditions to effect brake application at the full service rate. For instance, the P2-A valve is illustrated as responding to an overspeed condition and/or to a foot pedal fault (absence of foot pressure on the foot pedal).
The brake equipment also includes a multiple unit valve 38 enabling the locomotive to be united with other locomotives as either a lead, trail or dead unit. The multiple unit valve 38 of a lead unit serves to signal trail units via independent brake application and release pipe 42 and an actuating pipe 43. In the lead position, multiple unit valve 38 connects the actuating pipe signal from brake valve 30 to the control valve 33 and actuating pipe 43 and connects the independent application and release signal from the brake valve 30 to the independent application and release pipe 42.
The prior art brake equipment is costly to manufacture as it requires substantial iron and aluminum castings for each of the pneumatic valves and is costly to install as it requires numerous pipe interconnections.
Computerized brakes are well known as shown by U.S. Pat. No. 4,402,047 to Newton et al. In this computerized brake control system, the computer calculates the desired brake cylinder pressure from commanded brake signals, vehicle weight, vehicle speed and dynamic braking and compares the desired brake cylinder pressure with the actual brake cylinder pressure. Then it controls the fluid brake system to cause the actual brake pressure to be substantially equal to the desired brake pressure. As illustrated in FIG. 2 of that patent, the brake control manifold 40 has an electromagnetically controlled apply valve 46 and release valve 48 under the control of computer to cause the desired brake cylinder pressure to match the desired brake cylinder pressure.
Another system which shows the use of magnetic valves for applying and releasing brake pressure is U.S. Pat. No. 4,652,057 to Engle, et al. Single control handle 76 is used in combination with a control panel 102 and a display 96. In both systems, the electromagnetically controlled valves control the specific pressure applied to the brake cylinders from a reservoir and does not control the pressure within the reservoir.
Prior systems have also included a substantial amount of fluid tubing which is costly to build and maintain. Similarly the interlocks between the propulsion and braking system have been mechanical and also a function of the operator.
Prior computerized brake systems, have not improved the response of the independent brakes. The control of the independent brakes is a function of the pressure buildup on the independent application and release pipe. Also, where the independent application and release pipe has failed, the computerized brake system did not allow control of the locomotive brakes.
Thus this is an object to present invention to provide a novel computer interface for a computer controlled rail brake equipment with an enhanced independent brake control.
Another object of the present invention is to provide a braking system which will accelerate initial response of the independent brake operation.
Still a further object of the present invention is to provide a computer controlled railway brake system which allows control of the independent brake for failure of the independent application and release pipe.
These and other objects of the present invention are achieved by providing a computerized locomotive control system which receives as inputs electrical signals representing braking control signals from at least an independent application and release controller and an independent application and release pipe and electrical signals representing leading and trailing modes. A computer determines desired pipe pressure signals in response to the braking control signals and determines brake cylinder control signals only in the leading mode in response to the braking control signals from the independent application and release controller and the independent application and release pipe. Pressure in said pipes and said brake cylinder are controlled in response to the desired pipe pressure signals and brake cylinder control signal. The computer determines the brake cylinder control signal also from said brake pipe and actuator pipe pressure signals. The brake cylinder includes a control reservoir and the computer determines a desired control reservoir pressure signal as the brake cylinder control signal in response to the braking control signals.
The computer means determines the brake cylinder control signal initially in response to braking control signals from the independent application and release controller and subsequently in response to braking control signals from the independent application and release pipe. Preferably, the computer determines the brake cylinder control signal in response to braking control signals from the independent application and release controller for independent application and release pipe pressure up to generally 20 psi and in response to braking control signals from the independent application and release pipe for independent application and release pipe pressure above generally 20 psi.
The computer also determines failure of said independent application and release pipe and determines the brake cylinder control signal in response to braking control signals from the independent application and release controller during failure of the independent application and release pipe. The computer determines failure of the independent application and release pipe when the desired independent application and release pipe pressure is above a first value and the independent application and release pipe pressure is below a second value less than the first value after a predetermined period of time.